A device described in Japanese Patent Application Publication No. 2008-179235 (JP 2008-179235 A, Patent Document 1) is already known as an example of the control device that controls a vehicle drive device as described above. In the following description in the “BACKGROUND ART” section, the names of members used in Patent Document 1 are cited in brackets for description. In the control device, in switching from an EV mode to an HEV mode, one [disengagement-side shifting friction element] of a plurality of shifting engagement devices of a speed change mechanism [automatic transmission 3] is brought into a slip engagement state. In this state, a disconnecting engagement device [first clutch 6] is engaged, and the rotational speed of a rotary electric machine [motor/generator 5] is raised to a predetermined target speed to crank an internal combustion engine [engine 1]. By causing the predetermined shifting engagement device to slip in this manner, occurrence of a starting shock due to transfer of unstable torque to wheels during such switching is relieved.
As recognized in Patent Document 1, in mode switching accompanied by starting of the internal combustion engine such as that described above, a target shift speed for the speed change mechanism is occasionally changed. In the device according to Patent Document 1, after the target shift speed is changed, supply of a hydraulic pressure to another one [engagement-side shifting friction element] of the shifting engagement devices to be engaged in order to establish the target shift speed after the change is started immediately.
When supply of a hydraulic pressure to a shifting engagement device is started, however, heat is generated little by little even before the shifting engagement device is brought into a slip engagement state. Therefore, if supply of a hydraulic pressure is started immediately as described above in the case where a shifting request is made at the same time as an internal combustion engine starting request is made, heat may be generated continuously for a long time (since the shifting request is made until the rotational speed of the internal combustion engine is raised) compared to the case of normal shifting control. As a result, there arises a need to enhance the heat-resistant performance of the shifting engagement device, which may lead to an increase in size of the device and an increase in manufacturing cost. It is also conceivable to delay the timing to start supply of a hydraulic pressure with respect to a shifting request in consideration of heat generation by the shifting engagement device. In this case, it is important to appropriately decide the supply start timing. In the case where the supply start timing is not appropriate but is too late, for example, initial hydraulic pressure supply for bringing the shifting engagement device into a state immediately before it starts generating a transfer torque capacity may be insufficient. Hence, the drive force may not be raised immediately after the rotational speed of the internal combustion engine and an input-side rotary member in the speed change mechanism reaches a rotational speed matching the vehicle speed and the target shift speed after the change.